Conan O'Brien wins 'HIMYM' walk-on role

Neil Patrick Harris has revealed that Conan O'Brien won a walk-on part in How I Met Your Mother at a recent charity event.

Harris, who plays Barney in the CBS comedy, was appearing on Conan on Monday night when he recounted how O'Brien bid for the cameo appearance while attending the benefit.

"One of the prizes [at the benefit] was a walk-on role on How I Met Your Mother which we offer sometimes for charities," he explained.

"Normally it's in a bar scene and we just sit the person over our shoulders so they can say, 'Look mom and dad, I'm on How I Met Your Mother!' [Conan] jokingly said, 'That's the only one I'm going to bid on!' I thought that was sweet but a lie!"

However, Harris went on to reveal that O'Brien kept outbidding himself for the prize and did secure the walk-on role.

O'Brien then said: "I kept bidding against myself and I won it. Later I heard from the producers and creators the show and they said they would write me in as a character. I think it's much funnier if I'm in the bar in the background!"

The Conan host joked that he would spend his entire time on screen drawing attention to himself in the background. "All you are going to keep hearing is cut," he told Harris. "Try it again! Conan, just settle down!"